“It is intolerable to see that in a democratic state it is not possible to have a normal campaign,” he said.

Mr Bolsonaro’s son shared an image of his father saying: “Jair Bolsonaro is stronger than ever and ready to be elected President of Brazil on the first round!

“God gives us another sign that good will triumph over evil. Thanks to all who give us strength at this difficult time! Brazil above all. God above all!”

The attack is a dramatic twist in what is already Brazil’s most unpredictable presidential election since the country’s return to democracy three decades ago.

Latest polls put Mr Bolsonaro in a clear lead with 22%, compared with 12% each for environmentalist Marina Silva and center-left runner Ciro Gomes.

Mr Bolsonaro, a retired army captain, is a controversial figure who has enraged many Brazilians with extreme comments, but has a devout following among conservative voters.

One of his campaign pledges has been to legalise the carrying of weapons in order to combat rising violent crime.

Image:Jair Bolsonaro, 63, was attacked during a campaign rally

Despite being a long-serving member of Congress, Mr Bolsonaro has successfully presented himself as an outsider, untouched by the corruption scandals engulfing Mr Temer and much of the political elite.

Yet he has also courted deep controversy with comments attacking women and sexual minorities, as well as for praising the country’s 1964-1985 military dictatorship.

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Sometimes described as Brazil’s Donald Trump, Mr Bolsonaro has a huge social media following of 8.5 million people.

The only Brazilian politician currently more popular is the leftist ex-president Luiz Inacio Lula da Silva, who is in prison for corruption and has been banned from competing in October’s election.